1

### JEE Main 2017 (Online) 9th April Morning Slot

A signal is to be transmitted through a wave of wavelength $\lambda$, using a linear antenna. The length l of the antenna and effective power radiated Peff will be given respectively as :

(K is a constant of proportionality)
A
$\lambda$, Peff = K $\left( {{1 \over \lambda }} \right)$2
B
${{\lambda \over 8}}$, Peff = K $\left( {{1 \over \lambda }} \right)$
C
${{\lambda \over 16}}$, Peff = K $\left( {{1 \over \lambda }} \right)$3
D
3

### JEE Main 2018 (Online) 15th April Morning Slot

The number of amplitude modulted broadcast stations that can be accomodated in a $300$ $kHz$ band width for the highest modulating frequency $15$ $kHz$ will be :
A
$20$
B
$15$
C
$10$
D
$8$

## Explanation

Given, modulating frequency = 15 kHz

$\therefore\,\,\,\,$ Bandwidth of one channel = 2 $\times$ 15 = 30 kHz

$\therefore\,\,\,\,$ No of stations = ${{300} \over {30}}$ = 10
4

### JEE Main 2018 (Online) 15th April Evening Slot

The carrier frequency of a transmitter is provided by a tank circuit of a coil of inductance 49 $\mu$H and a capacitance of 2.5 nF. It is modulated by an audio signal of $12$ $kHz.$ The frequency range occupied by the side bands is :
A
13482 kHz $-$ 13494 kHz
B
442 kHz $-$ 466 kHz
C
63 kHz $-$ 75 kHz
D
18 kHz $-$ 30 kHz